Which of the following measures is important to ensure when sampling wastewater?

Controlling sampling site conditions is crucial for obtaining accurate and representative samples of wastewater. Ensuring that the conditions at the sampling site are consistent allows for more reliable data collection and minimizes the potential for contamination or variation due to external factors. This includes monitoring factors such as temperature, flow rate, and any disturbances that could affect the sample.

When site conditions are controlled, it helps ensure that the sample reflects the true composition of the wastewater. This consistency is important for analyzing the chemical and biological parameters of the sample, which can be influenced by variable conditions if not properly managed. Data integrity is paramount in wastewater sampling, and maintaining stable conditions at the site directly contributes to that goal.

Sampling at random times and ensuring system pressure is stable are important practices, but they do not directly ensure the integrity of the sample collected at the site, making controlling site conditions the most critical measure in this context.